Differential mechanism



I. HUPP.

DIFFERENTIAL MECHANISM.

APPLICATION FILED MAY 2. 1919.

Patented June 27, 1922.

2 SHEETS-SHEET I.

I. HUPP.

DIFFERENTIAL MECHANISM.

APPLICATION FILED MAY 2, 1919.

Patentd June 27, 1922.

2 SHEETS-SHEET 2- UNITED, STATES PATENT .o'rricg;

mviu summon CHICAGO, ILLINOIS, ASSIGNOR TO rLExo MOTIVE CORPORATION 01* DELAWARE.

CORPORATION, A

DIFFERENTIAL MECHANISM. v

.T 0 all whom it may concern Be it known that I, IRvIN HUPP, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Differential Mechanism,-0f which the following is a description, reference being had to the accompany ingdrawings, which form a part of my specification.

My inventlon relates todifferential mechanism more especially intended in connection with motordriven Vehicles and has for its object the provision of a construction driven wheels in advance of the other will wheremthe spinning of one of the powerbe made impossible and the power equally transmitted to, both wheels under all conditions: it being understood, of course, that the speed of one wheel induced through the pulling action or movement of the chassis,

as against the others may be accelerated to a predetermined extent in order to permit thevwheels to describe the arcs of different circles. v

- ,My invention has for its object the provision of mechanism whereby the power will be prevented from entirely passing through to the wheel presenting the least resistance;

said mechanism being adapted to automatically move different portions of the elements into interlocking relation during varying conditions or manner of operationof. the differential mechanism,

The objects and advantages offmy inven a tion will be more fully comprehended, from v the following detailed description of the accompanying drawings, -which latter I believe present the best'emhodiment of the invention, butit be understood that it departing from the spirit of the invention,

In the drawings t 1 Figure 1 is a top plan view of my improved construction shown appliedto the -on thelinei33 of Figure 1,

direction 'of'the arrows.

sectional driving axle of a vehicle; the outer or wheel ends of the axle being broken away.

' Figure 2 is. a longitudinal sectional view, taken on the line 2- -2 of Figure 1,'lo0king in-the direction of the arrows.

Specification o f ietters Patent.

Intent-ea Jae 275 71922) Application filed May 2', 1919; Serial no. 294,133Q

Figure 4 is a partial side elevation and I cross-sectional view, taken on the line H of Figure 1,; lookinginthe direction ofthe arrows.

Figure 5 i'sa detail cross-sectional view of the innei ratcheting mechanism, taken on the line 55 of Figure 2 looking in the dlrectio'n of the arrows;

Figure 6 is a detail cross-'sectional -view of the outer ratcheting mechanismytake'n on the line 6-6 of Figure 2;'

In the particular"exemplification of the invention it is shown applied to what'purports to be the rear axle of "a motor-driven The inner or'adjacent ends of "the two 's'ec-'- tions are mounted in the hubs of the ratchets ing elements of "the differential mechanism later to be described; the inner ends of the two axle-sections being held in propermlignment by means of a suitable pin 16; The Y. inner ends of axle-sectionsare spaced apart so as to enable the pin 16 to provide a journal bearing for a 'worm-wheel17 which is loosely mounted thereon. The worm-wheel 17 'is adapted tomesh with the usual worm shaft which leads from the transmission mechanism of the vehicle and transmits" power to the'worm-wheel' 17 and, by means of suitable mechanism later to be described,

to the respectiveaxle-sections. The sides of theworm-wheel '17, intermediate of the I hub-portion and outer perimeter or worm a portion thereof are provided with ratchet mechanisms shown in the nature of'annular members or rings arranged concentrically on both sides of the worm; theouter faces 18, '18 and 19, 19, respective1y;1the annular members or rings being secured to both.

of said members being provided with teeth sides of the worm-wheel 17 by means of the rivets 20, 20, see Figures2 and 3. Disposed on both sides of the worm-wheel 17 are similarly constructedshell-sections 21 and 22, having inwardly'presented periph-J 'eral portions or flanges provided with I ratchet teeth 23 and 24, respectively, disposed toward opposite sides of worm wheel 17 and adapted to engage with-the teeth 18,18 of the adjacent ratchet mechanism secured to the sides of the worm wheel 17. The shellsections 21, 22 are each provided with .elon-' gated hubs which are'slidably mounted or feathered on theUhub-Zportions 25 and 26,-

and 26. respectively, as shown in Figure 2.

The hub-portions L5 and 26 of the inner ratchet mechanism are internally squared and slidably mounted on their respective axle-sections 15, 15 see Figure 2-. The ratchet-wheelsQT. 28. like the shell-sections 21 and 22, are somewhat "in the nature of crown-gears, namely with their teeth dis posed toward the worm-gear 1.7; and these teeth are intended to mesh with the teeth 19 of the inner concentrio rings secured to opposite sides of the worm-wheel 17,. The ratchet-wheels 27 maintained in mesh "with the teeth 19 on worn'i-wheel .17 through the action of the springs 29 and 30, respectively: the springs being disposed about the axle-sections l5, 1:") and maintained in pressuI e-applying position by means of suitable stops or collars. as at 31. properly secured to the axle-sections.

'ith the transmission mechanism of the motor-driven vehicle transmitting power in ya manner so as to drivethe vehicle forwardly. the worm-wheel 17 will rotate in the direction of the arrow in Figure l such rotation will present the flat surface of the teeth forwardly relative. to the direction of rotation and therefore will induce or permit the teeth of ratchet-wheels 27 and 28 to re- .main inrateheting or meshing relation with the teeth 19 of the inner annular members on the sides of worm-gear as shown in Figure 2 and therefore will transmit power ina similar direction to both axle-sections 15. l5 .-therel' v causing the vehicle tobe driven forwardly It is evident from my improved construction shown that power will be equally transmitted to both traction wheels in the operation of my improved differential mechanism becauseof its locking nature. In other words, it is apparent that the difi'erential mechanism cannot rotate at a-greater speed or ahead of the speed of the wheels. ()n the other hand. l'iowever. the traction wheels may rotate at a speed greater than the speed of the differential wormwheel. because ofthe vielding relation between 1:lt('l1l-\\'lltl.'-i QT and 28 and the teeth lil of the inner ratchet mechanism as forexample H1 driving the vehicle forwardly in a circle or through the arc of a circle. one of the traction wheels is caused. through the pull of the chassis. to move at a greater speed than the other traction wheel because of the fact that it is forced to move through the art-of a larger circle than theopposite-wheel.

.\s the traction wheels are fixedly. secured to theirrespective :lXlWHtt'titHlH so as to rotate therewith. they will cause the respecand 28 are vieldingly member 34.

inclination. it is evident that rotation of a wheel at greater forward speed thanthe differential worm l7. and therefore also faster than the corresponding annular toothed member on the side of the worm. will allow the ratchet mechanism or ratchetwheel on the same side as the fast moving wheel and axle-section to slip out of ratcheting engagement; this unratcheting action being made possible by the slidable relation between the ratchet-wheels and the axlesections and the springs 29 and 30 whereby the ratchet wheels are maintained in operative relation. For example. we will assume that the wheel secured to the right hand axlesection 15. in l igure 2. is-caused to describe the arc of a larger circle than the wheel secured to the left hand axle-section in said figure (such movement of the wheels being 'induced through the chassis of "the steering wheels) the speed of the wheel on the right hand side in said figure will be greater than the speed of the wt'n'm-wh'ee'l IT. This will cause the teeth of ratchet-\vhcelit to slide out of ratcheting relation with the teeth 19. secured to the side ofthe wormwheel 17: and this will induce ratchet-wheel 28 to move lengthwise of its axle-section 15 against the action of spring 30. compressing the latter. During this action. ratchetwheel 27 will still remain in mesh with the teeth of annular member 19 on the left hand sideof worm-wheel 17.

The outer ends of the hubs 25 and '26 of ratchet-wheels 2T andQR. respectively. are both provided with enlarged portions or-"collars rn'eferablvprovided with grooves -32 and 33. respectively. The groove 32 inthe elongated hub of ratchet-wheel 27 is adapted to receive the ends of a voke or fork- The relation between the ends of vokc. 3i and the hub of the ratchet-wheel is such.however. as to permit the ratchet-5- whcel to rotate: while .the yoke 01 b cated member 2H has a iixed pivotal point at 2-35 secured to a stationary portion "or bar 36 of the underframe of the vehicle: the pivotal point 35 of the voke 34 being prefer 'ably' at a point intermediate of the 'ends of link or fing-rod 48' and yoke hubs Whose outer ends are also provided with c rcumferential grooves 40 and 1h re-- spectively. The circumferential groove 10,

of shell-section 21, is intended to receive the bifurcations of a yoke ornien'iberlzl which is pivotall) secured intermediate of its ends at 43 to a stationary frame-member 44:; while the groove 11 in the hub of shell-section 22 is adapted to receive the bifurcations of a similar yoke member 45, which is pivotally mounted intermediateof its ends at @G to a. stationary frame member 47, see F igures 1and2.- a

The 'out'er end of yoke member 31 hashec'oniiecting rod 48 pivotally secured thereto at 49; while the opposite end ofth'e link or connecting rod 48 has operative connection with the end of yoke membei lfi, so that movement of inner 'ratchet-meniber27 lengthwise of it's axle-section 15 and outof. ratcheting relation with teeth 19 will be transmitted, by means of yoke 3 1, connect- 15 to outer ratchetwheel or shell-section 22. The action of the elements just referred to will induce the outer ratchet-wheel 2:2 to move toward worm-wheel 17. The action justdescribed' is yieldiiigly transmitted to the outer ratchet-whe'el or shell-section 22 by means ofa spring 50 encircling coii iiti'iig-rod 48. with one end of the spring bearing against a c0llar orliaiige 51. secured to co'iiiiectiiig-i'od -18, while the other end of the spring bears against the outer end of the yoke 4:); the

connecting-rod 48"beingr held against with-.

drawal froi'n tlie 'end of yoke member 45 by means of a suitable cotter pm as at ingz-rod 18 is shifted so as to place spring 50 under compression. ratchet-wheel or shell-section 22 will be yieldingly forcedtoward its respective ratchet-teeth 18-seciired to the worm-wheel 17;

v tween ratchet-wlieelor shell-section 22 and the teeth 18 on worm-wheel 17 while the worm-wheel 17 is still'moving in'a 'forwardly driving direction. I

' Tlic yoke 37 operatively secured to the outer end of hill-i226 of inner ratchet wh'eel 28 has its outer end provided with a coniiecting-rod or link 53 pix'otallv secured thereto. at 54, while the opposite end of the link 53 is yieldingly secured b v means of a. spring to the outer end of yoke42which latter has operative relation with the opposite outer ratchet-wheel or shell-section 21. The connecting link is maintained in operative relation with yoke member 42 by a suitable cotter pinas at 56 so as'to prevent its accidental withdrawal. i

It willvbe understood from the foregoing description that the inner ratchet wheels or sections 27 and 28 are intended to' be iii'conis not in thedepression or 'mud-ho The. action of spring 50 is similar to the tK'llOli ofsprings 2S) and 30. namely when connecttudinally of, axle-scction 1:"

spring 30, and. as a- 'esiilt, also cause oscillaab'out its pivotal point 38,

I infother words, en. ahling a non-ratcheting relation to exist be-' stant ratcheting relation with teeth 19 secured to both sides of worm-wheel 17 when the worm-wheel of the vehicle to' n ove forwardly; and both aide sections-and therefore also both [tractiondifferential mecha}. nism 1S rotated in a direction to c-ause'the;

wheels will be "caused to rotate at similar speeds. In the event of one of the tractionwheels entering aidepression or nud-hole,

both wheels will nevertheless be caused to rotate jgat equal spee d,'so that traction or power will be obtained from both wheels; in other words, the wheel in the depression or mud-holewillnot, as is the case with differential mechanism at oresent employed, have :all of the powert -ansn itted to be I cause of the fa'ctthat it offers less resistance than the other wheel. \Vith thepower tr'ansto the wheel which initted in an} equal degree le and therefore in traction-producing position,

is. evident that the vehicle can more readily be driven and pulled out of any ruts or mudli'oles. g'lhis cond tion or operation is in duced by. reason 0 the positive or look ng iiatureofumy improved differential m'echanism. 1 i i i I In the assumed operationwhere the wheel oiithe, right handaxle-section 15 in. Figure 2 is describing the arc of ,a larger circle, and therefore travelingat a fasterspeed than the v 28 ()ll' tllt righthand side of the Worm-wheel tion 1 of, yoke 37 i in such manner asto move connecting-rod .or link 53 to the left in Figure Such movement of yoke 37- and connecting-rod 53 willioscillate yoke meniberflQ about its pivotal connection 13 ill-811th {manner as to 111- duce outer ratchet member or shell-sect on 21. on the left-hand side of worm-wheel 17, to be moved toward its respective ratchet element or teeth 18 on the worm wheel 17.

In vview of the construction of the ratchet teeth 18 and 523 of ratchet-wheel 21 being similar to the ratchet teeth of the inner ratchet element or mechanism, (but with the. interlocking surfaces .di'rectionsi it is evident that theratchetdisposed in opposite teeth 23 of outer ratcliet section 21 will merely slide-overthe teet h 18'aslong as the axle-section 15 to. the left ofthe \vorm wheel 17 rotates forinj'ardlwi The outer "ratchet mechanism 21 is yieldin'g'ly forcedto'ward teeth 18 by theractionofsprinQ' on con necting-rod' 53 "dur ng the operationfdescribed, thus permitting the slipping i'felation between the teeth while the worm-"wheel 17 and the ratchet-elements secured thereto are rotating in a forwardly driving direction.

It will be understood, of course, that a similar operation will take place on the left hand side of worm-wheel 17, so'far as the inner ratchet mechanism 27 is concerned, and on the right hand side so far as outer ratchet-elementor shell-section 22 is concerned. when the wheel secured to the left hand axle-section is induced to describe the arc of a larger circle and therefore travel at a faster speed than differential worm-v wheel 17.

With this condition it will be understood that inner ratchet section 27 will be caused to move lengthwise of its respective axlesection, namely to the left against the action of its spring 29, thereby oscillating yoke 34 a about its pivotal point 35, forcing connecting-rod 48 to the right, see Figure 1, which will cause yoke member -15 to force outer ratchet element or shell-section 22, on the right hand side of the worm-wheel 17, toward the teeth 18 located on the same side of the worm-wheel, and therefore in position to lock the axle-section 15 on the right of the worm-wheel 17 against any backward movement during the forward movement of the vehicle.

Where the vehicle is intended to be driven backwardly, in other words where the differential worm 17 is rotated in the opposite direction tothat previously assumed, the rear or sloping sides of the teeth 19, 19, on both sides of worm-wheel 17 and the teeth of inner ratchet-wheels or elements 27 and v 28, will cause the inner ratchet-wheels 27 and 28 to move out of ratcheting position and lengthwise of the axle-sections against the actions of their respective springs 29and 30. Such movement of the inner ratchet elements also cause oscillation of the respective yokes and connecting-rods, which will force the outer ratchet elements or shell-sections 21 and 22 into position where their teeth 23 the wheels to rotate through the arcs of different circles without, however, permitting any sliding condition to arise; the ratchet mechanisms on one side of the worm-wheel, to-Wit the side which is intended to rotate faster than the rotation of the worm-wheel,

being adapted to be out of meshing relation while the ratchet mechanism on the opposite side of the worm-wheel will be in meshing position. On-the other hand, however, it will be impossible for the worm-wheel to turn at a faster speed than either one of the parting from the spirit of the invention, as

expressed in the appended claims.

. lVhat I claim is 1. Differential mechanism, comprising, in combination with a pair of axle-sections, a main power-imparting gear mounted ooaxially with said axle-sections, the power-imparting gear being provided with a pairof concentrically arranged circular ratchetwheels on both sides of said gear, with the teeth of the two circular ratchet-wheels on each side of the gear being oppositely disposed, a pair of concentrically arranged independently. movable ratchet-members on each side of said gear adapted to mesh with the ratchet-wheels secured to the sides of other ratchet-member of each pair will be held out of ratcheting relation so that rotation of the power imparting gear faster than the axle-sections is automatically prevented. I v

2. Differential mechanism, comprising, in combination with a pair "of driven shafts, a loosely mounted power-imparting gear disposed between the shafts, a pair of ratchet elements disposed on each side of the powerimparting gear, each pair of ratchet elements being arranged in operative relation with the shaft disposed on the same side of said gear and adapted to have operative engagement with said power-imparting gear, a portion of said ratchet elements being adapted to rotate their respective shafts forwardly while the other portion of said elements is adapted to rotate their respective shafts reversely, and means whereby different portions of said ratchet elements are brought into operative engagementwith said powerimparting gear when the latter moves in opposite directions, said last means being adapted to also cause one of the ratchet elements on each side of the power-imparting gear to have operative relation with said gear and prevent the latter moving faster than either driven shaft.

3. Differential mechanism, comprising, in combination with a pair of driven members, a rotatable power-impartingmember loosely mounted intermediate of said driven members, a pair of members arranged on each driven member and 'in slidable operative relationtherewith, said members being adapted to form operative relation with said powertransmission of power from the power-mi- ..partingfmember to both driven members and rotation of the former in advance of the latter prevented. and means whereby a selective member of both pairs of members is forced intofengagement with said power- 1mparting member. said means being con trolled by. the direction of rotation of said rotatable pmver-imparting member.

4. Diterential mechanism.comprising. in combination with a sectional axle. a main pmve'r-transmittiag member provided with ratchetsurfaces. a pair of concentrically arranged ratchet-men]bers disposed on opposite sides of said power-transmitting members and arranged in slidable operative,

relation with the respective axle-section disposed on the same side of said power-transmitting member. and means adapted to be.

atl'cA-ted by the concentrically arranged ratchet-members whereby one. ratchet-member of each pair will be maintained in ratcheting relation with certain of the ratchct-surtaces of said first member and movement of the first member at a speed in advance of the axle-sections prevented.

5. Ditt'erential mechanism. comprising. in combination with a sectional driven member. a main power-transmitting member provided with ratehet-surt'aces concentrically arranged on both sides of said power-transmitting member. a pair of coiicentrically arranged ratchetmembers on both sides of said power-transmitting member and arranged in slidable operative relation with the respective section of the driven-member disposed on the same side otthe-powertransmitting member. and means adapted to be ati'ected by the. concentrically arranged ratchet-menibers whereby one-ratchet-member of each pair will. be. maintained inratcheting relation with certain of the ratchet-surfaces ot said po\ve1.'-transmitting member and movement of the latter at a speed in advance. of the driven member-sections prevented.

6. Ditl'erential mechanism; comprising. in tflnlliilltltitlll with a sectional driven-member. a pmver-imparting member. a plurality of slidable elements ope-rativelv secured to each driven member-section so as to rotate therewith. said elements being adapted to have operative. relation with the power-imparting member. and means whereby a, portion of said elements is maintained out of operative relation while the other portion of said elements is in operative relation with said power-imparting member and movement of the power-imparting member. in advance of the sectional driven member prevented.

7. Ditlerential mechanism. comprising, in combination with a pair of driven members. apower-imparting member coaxially arranged with said driven members but normally out of operative relation-therewith, said power-imparting member beingprovided with a plurality of concentrically arranged engaging portions. a pa'i1"'ofe0ncen trically. arranged members havingslidable operative relation with-the adjacentendsot tive relation with its respective engagingsurface on the power-transmitting member. and means intermediate of the pair of concentrically arranged members on opposite sides, of the powtertransmitting members whereby the non-operating member on one side of the 1 ower-ttransmitting" member is moved into engagement with its'respective engaging portion on the power-transmitting member when the operatively engaged member of the pair of concentrically arranged members. on the opposite side of the powertransmitting member is forced out of operative engagement with its respective engaging portion on the power-transmitting membe'ri s. Diti'erential mechanism. comprisin in i combination with a pair of alined driven members. a power-transrmtting member disposed between the tHlJEH'tIlt ends of the driven members and provided with ratchet-- teeth on both sides thereo t. a pair of concentrically arranged ratchet-members disposed on opposite sides of said power-transmitting member and in slidab'le operative relat'ion driven-members. means whereby one ratchetmember ofeach pair is normally held in yielding operative relation with portions of the ratchet-teeth on said p )wer-transmitting member.- and means intermediate of the concentrically arranged ratchet-members on.

both sides of the power-transmitting member whereby movement of one driven member in reverse direction to the movement of the driven member on the opposite side of the 1)ower-transmitting member will be prevented.

9. Ditterential mechanism. comprisi ng','"in

with the ends of the respective i operative relation while the other portion is in operative relation with said powertransmitting member.

10. Differential mechanism, comprising, in combination with a pair of aligned driven shafts. a ')ower-imparting gear loosely journaled at the inner adjacent ends of the shafts and provided with circumferentially arranged sets of ratchet teeth on both sides thereof. a pair of concentrically arranged ratchet members on the adjacent ends of both driven shafts adapted to'have operative relation with said power-in1parting gear and thereby transmit power to the respective driven shafts. one ratchet member on each driven shaft being adapted to cause forward rotation while the other ratchet member on each driven shaft is adapted to cause reverse rotation. and means whereby selective members of both pairs of ratchet members. but on different driven shafts. are automatically brought into operative relation with the power-imparting gear while the other members of both pairs of ratchet members are out of operative relation with said gear, whereby rotation of the power-imparting gear faster than either driven shaft will be prevented.

l1. Differential mechanism, comprising, in combination with a pair of aligned driven members, a power-imparting member loosely mounted intermediate of the adjacent ends of said driven members, a pair of ratchetmembers on each side of said power-imparting member and concentrically arranged in slidable operative relation with the adjacent end of each driven member, one ratchet-member of each pair being adapted to have ratcheting relation with said powerimparting member when the latter rotates in one direction while the other member of each pair of ratchet-members is adapted to have ratcheting relation with said power-imparting member when the latter rotates in the opposite direction, and means intermediate of both pairs of ratchet-members whereby one member of each pair is simultaneously forced into operative position and positive rotation of both driven members in the same direction induced.

12. Differential mechanism, comprising, in combination with a pair of drivenshafts or axles, power imparting means, a portion whereof is adapted to drive the shafts in a forward direction while the other portion is adapted to drive the shafts in reverse direction, means whereby a positive interlocking relation between the first means and both shafts or axles is induced in the direction of rotation of the first means, a portion of the second means operatively connecting-a part of the forwardly driving portion of the first means on one shaft with a part of the reversely driving portion of said first means on the other shaft, whereby rotatween the first means and both shafts or axles is induced in the direction of movement of the first means. and means whereby the second means are yieldingly forced into contact with the first'means so as to per mit movement of the shafts or axles relative to the first means in the same direction of rotation while non-rotation of one shaft or axle relative to said first means or reverse movement of either .shaft or axle relative to the other and to the first means will be prevented.

H. Differential mechanism comprising,in combination with a pair of shafts or axles arranged in aligned relation, power-imparting means disposed between the. adjacent ends of the shafts or axles, a pair of con-.

centric members operatively secured on each axle or shaft adjacent to said power-imparting means and adapted to have meshing relation with said means, one member of each pair being adapted to mesh when said means rotates in one direction while'the other members mesh when said means rotates in the opposite direction, means for yieldingly holding one member of each pair in meshing relation with said first mentioned means. and means intermediate of the inner member of one pair and the outer member of the other pair of concentric members whereby movement of the normally meshing members into a non-meshing position will induce a member on the opposite side of the power-imparting means to move toward said means.

15. Differential mechanism, comprising, in combination with a pair of aligned shafts or axles, power-imparting means disposed between adjacent ends of the shafts or axles, a pair of concentric ratchet members operatively secured on each axle or shaft and arranged to have sliding relation therewith, said ratchet members being adaptedto mesh with said power-imparting means. one member of each pair being normally in ratcheting relation while the other niembe' of each pair is normally out of ratcheting relation, means whereby the normally ratcheting member of each pair is yieldingly held in ratcheting position. and means intermediate of the normally ratcheting member of each pair and the other member of the opposite pair whereby movement of either one of said normally ratcheting members into nonratcheting position will induce the other member of the opposite pair to more toward ratcheting position with said powerimparting means, the first mentioned member of each pair being adapted to mesh with said power-imparting means when the latter rotates in one direction while the second mentioned member of each pair. is adapted to mesh with said means when the latter rotates in the opposite direction.

16. Differential mechanism, comprising, in combination with a pair of aligned shafts or axles, a worm-wheel rotatably mounted intermediate of the adjacent ends of said shafts or axles and normally out of operative relation therewith, said worm-wheelibeing provided with ratcheting surfaces on both sides thereof, a pair of concentrically arranged ratchet-members operatively secured to the adjacent end of each shaft or axle and adapted to have movement lengthwise thereof, means whereby one member of each pair of ratchet-members is normally ing members and the other or normally non-e ratcheting member of the opposite pair whereby movement of the normally ratchet- I ing member out of ratcheting position will induce moven'ient ot' the second mentioned member of the opposite pair toward ratcheting position. one ratchet member of each pair being adapted to mesh with the ratchet surface of the worm-wheel when the latter rotates in one direction, while the other member of each pair is adapted to mesh with the ratchet surfaces of said Worm-Wheel when the latter rotates in the oppositedirection.

IRVIN HUPP. 

